The pending storm, which threatened to bring as much as 3 feet of snow and high winds, prompted residents across the state to stock up on emergency essentials, as employers ordered staff to work from home, schools closed, and thousands of National Guardsmen prepared to help with the aftermath.

Governor Deval Patrick had one ­message for residents: Stay inside.

“Accumulation is expected to be swift, heavy, and dangerous,” Patrick said.

Nonessential state employees have been asked to work from home Friday, and Patrick urged private companies to do the same.

The predicted 2 to 3 feet of snow will be lashed by winds gusting up to 65 miles per hour into drifts as deep as 5 feet, the National Weather Service said Thursday.

The Weather Service warned that the storm would pose a threat to people’s lives and property and that conditions would deteriorate quickly as the storm develops Friday. Travel will become nearly impossible by the Friday evening commute into Saturday.

“The sooner you can be off the roads the better,” said Weather Service meteorologist William Babcock. “You want to give yourself some time to be at your safe spot before the storm hits its strongest.” The Weather Service issued blizzard warnings for all of Eastern and Southeastern Massachusetts.

The MBTA, buses, and commuter rail will stop running at 3:30 p.m. Friday, ahead of the worst of the storm. Officials hope to have the T up and running again by Monday.

Residents’ rush to stock up caused its own problems Thursday. In what appeared to be the epitome of the frenzy to prepare, so many people were shopping that the Salem Fire Department responded to the Market Basket supermarket for overcrowding, a fire official said.

Declaring that Boston is ready for what may be a historic blizzard, Mayor Thomas M. Menino canceled school in the city for Friday and urged people to stay off roads and out of downtown.

“We haven’t had a snowstorm of this size in many years,” Menino said. “We are hardy New Englanders used to these storms, but we want people to use common sense and stay off the streets.”

Before dawn Friday, 200 plows and salt spreaders will be crisscrossing roads in Boston, Menino said. By 9 a.m., officials plan to increase the number of plows and salt spreaders to 600. Boston will increase the number of public safety officials on the streets as well, he said.

A snow emergency will take effect at noon Friday, which bans parking on major thoroughfares. Roughly 15,000 parking spaces will be available at discounted rates at dozens of private and municipal garages. Friday trash pickup will be moved up to 6 a.m. in an effort to get garbage trucks off streets early.

At a State House press conference, Transportation Secretary Richard A. Davey said crews would pre-treat roads with salt Thursday night.

Patrick said he hopes residents will heed warnings to stay home and allow plows free range, but, he said, “if I have to order the roads to be cleared, I will.”

By Thursday morning, the MBTA said, crews had covered exposed electrical connections on Green Line cars to prevent freezing and damage from snow and inspected sleet scrapers on subway cars.

T officials decided to keep the system running until 3:30 p.m. Friday to allow first ­responders and hospital workers to get to their evening shifts and home from day shifts.

Several trains will be run slowly along the lines throughout Friday night to keep the rails clear of snow, though those trains will not be accepting passengers.

This is the third time the T has shut down service in the past 18 months due to weather concerns, Davey said.

Beverly A. Scott, the general manager of the MBTA, said she and Davey decided to halt service after forecasts reported an increased severity of the storm.

“There is nothing heroic about pushing the envelope ­beyond which you know you should,” Scott said. “It does no one any good to have 40-foot or 60-foot buses stuck all over the streets.”

As soon as it is safe, Scott said, T staff will attempt to ­restore service to trains and buses.

“We will do everything we reasonably can and possibly can to minimize the downtime,” Scott said.

“The good news is that we have two days to get ready for Monday morning rush hour,” Davey said.